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Salt stress in rice

adaptive mechanisms for cytosolic sodium homeostasis

Kader, Md. Abdul (2006). Salt stress in rice. Diss. (sammanfattning/summary) Ultuna : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2006:57
ISBN 91-576-7106-0
[Doctoral thesis]

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This thesis concerns salt stress in plants, particularly sodium (Na+) stress. A high concentration of Na+ in the cytosol interferes with many K+-binding enzymes and thus, hinders the metabolic activities in cells and is termed as Na+ (ionic) toxicity. Two important aspects of Na+ toxicity in rice (Oryza sativa L. cvs. Pokkali and BRRI Dhan29) cells are described: i) how Na+ is transported into and out of cells, and ii) how cells react by changing cytosolic Ca2+ and pH for activation of the adaptive responses. Under salt stress the ability to reduce Na+-influx into the cytosol, and subsequently increase the compartmentalization of cytosolic Na+ into the vacuole, appeared to be the significant salt-tolerance determinant in the salt-tolerant rice cv. Pokkali. These mechanisms were either absent, or less efficient, in the salt-sensitive rice cv. BRRI Dhan29. A lower Na+-uptake in cv. Pokkali, compared to that in cv. BRRI Dhan29, depended on different types of transporters involved in these two cultivars. In cv. BRRI Dhan29 the transporters mediating Na+-influx were K+-selective channels and NSCCs, whereas NSCCs were the main pathways for Na+-uptake in cv. Pokkali. Apart from the lower Na+-uptake, cv. Pokkali seemed to take up Na+ only transiently and extrude it mainly into the vacuole. Moreover, to maintain a low cytosolic Na+/K+ ratio, Pokkali also might have increased K+-uptake under salt stress. The study indicates that Na+ must be sensed inside the cytosol, before any changes in cytosolic [Ca2+]cyt and [pH]cyt occur. Sensing of Na+ differentially induced [Ca2+]cyt and [pH]cyt changes in the two rice cultivars. Also, the sources for the changes of [Ca2+]cyt and [pH]cyt were different in the two rice cultivars. Internal stores in cells like vacuole and ER appeared to be the major sources for [Ca2+]cyt increase in cv. Pokkali, whereas the apoplast was more important in cv. BRRI Dhan29. The [pH]cyt was differentially shifted in the two rice cultivars, in response to salt stress, and was coupled to different H+-ATPases.

Authors/Creators:Kader, Md. Abdul
Title:Salt stress in rice
Subtitle:adaptive mechanisms for cytosolic sodium homeostasis
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2006
Number of Pages:44
ALLI. D'Onofrio, C., Kader, M.A. & Lindberg, S. 2005. Uptake of sodium in quince, sugar beet and wheat protoplasts determined by the fluorescent sodium-binding dye benzofuran isophthalate. Journal of plant physiology 162, 421-428. II. Kader, M.A. & Lindberg, S. 2005. Uptake of sodium in protoplasts of salt-sensitive and salt-tolerant cultivars of rice, Oryza sativa L. determined by the fluorescent dye SBFI. Journal of experimental botany 56, 3149-3158. III. Kader, M.A., Lindberg, S., Seidel, T., Golldack, D. & Yemelyanov, V. Sodium sensing induces different changes in free cytosolic calcium concentration and pH in salt-tolerant and -sensitive rice cultivars. (Submitted). IV. Kader, M.A., Seidel, T., Golldack, D. & Lindberg, S. Expressions of OsHKT1, OsHKT2 and OsVHA are differentially regulated in a salt-sensitive and a salt-tolerant rice cultivars. Provisionally accepted for publication in the Journal of experimental botany.
Place of Publication:Ultuna
ISBN for printed version:91-576-7106-0
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:oryza sativa, varieties, salts, osmotic stress, salt tolerance, soil salinity, sodium, toxicity, ions, soil transport processes, nutrient uptake, homeostasis, chemiluminescence method, microscopy
Keywords:salt stress, Na+ toxicity, Pokkali, BRRI Dhan29, fluorescence microscopy, Na+ transport, confocal microscopy, Ca2+ and pH signaling
Permanent URL:
ID Code:1095
Department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Deposited By: Kader Md. Abdul
Deposited On:20 Sep 2006 00:00
Metadata Last Modified:02 Dec 2014 10:09

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